Axle Question
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Laughing Gas
Joined: Jun 2007
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Axle Question
I have a 76 F-100 "Ranger" I would like to stick a 3:50 Posi unit in. The big question is if it has 28 spline or 31 spline axles. Short of pulling an axle, is there any way to externally determine which axle is in the truck?
Laughing Gas
Joined: Nov 2003
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From: southeren Oh
Ther is a way but it is not foolproof. Look at the center of the axle shaft right in the middle of the wheel. Do you see a flat surface with three holes? Or do you see a large crater with two nubs at the edge? Generaly three holes is 31 spline. Crater is 28 spline.
Three hole axles have been known to cut down to 28spline, Rare but it can happen.
Three hole axles have been known to cut down to 28spline, Rare but it can happen.
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A posi unit won't fit in a Ford differential.
You would need a Ford Limited Slip or Traction-Lock diff.
You didn't say what ratio diff is in it now. What is the axle code on the door plate
I'll check my book for you to see what they list.
I suspect it to be a 31 spline.
You would need a Ford Limited Slip or Traction-Lock diff.
You didn't say what ratio diff is in it now. What is the axle code on the door plate
I'll check my book for you to see what they list.
I suspect it to be a 31 spline.
Last edited by Mil1ion; Aug 14, 2007 at 07:38 PM.
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Laughing Gas
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Thanks for the info Broncoman. I will take a look at it and let you know. According to the doorplate, it is supposed to be a 3.00, but I don't think it is right. This truck came from CA, and according to the various stickers was used by a rodeo cowboy. Although the body was solid, the mechanicals had been gone through several times. Sorry about the Posi reference. I use the term generically.
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Laughing Gas
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OK guys, had a chance to look at it today. The axles have 3 holes. The axle code is 12. The full code is 117A F100 BA3 F12J.
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I have to check my book.
That's one reason the axle code tags on 9" diff's are so important.
EDIT:
After further review, I would agree with a 31 spline.
There is only slight mention of the 2.9M axle and it pertains to bearings.
That's one reason the axle code tags on 9" diff's are so important.
EDIT:
After further review, I would agree with a 31 spline.
There is only slight mention of the 2.9M axle and it pertains to bearings.
Last edited by Mil1ion; Aug 16, 2007 at 08:48 PM.